> 2) adding new functionality requires addition of new keywords
There are reserved keywords and unreserved keywords. The latter can be used as table/column/function/etc names, and don’t cause any trouble.
New syntax can be invented by reusing existing reserved keywords, and introducing new unreserved keywords in places where they can’t be misinterpreted.
Not saying the problem you describe isn’t a problem, just that it’s slightly more complicated and not as bad as one might think when reading your comment.
2) adding new functionality requires addition of new keywords
3) you cannot define new keywords from SQL
4) despite standardization, each implementation differs
this article summarizes it pretty well, while i do not agree with everything in it it points out flaws pretty well.
https://www.scattered-thoughts.net/writing/against-sql/